/**
 Copyright (c) 2007, Alek Dembowski

 All rights reserved.

 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 * The names of its contributors may not be used to endorse or promote products derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

package com.darkpegasus.util.iteration;

import java.util.Iterator;

/**
 * @author alek
 */
public class IntegerRange implements Iterable<Integer> {
    int start, end;

    public IntegerRange(int start, int end) {
        this.start = start;
        this.end = end;
    }

    public Iterator<Integer> iterator() {
        if (start <= end) {
            return new ForwardIntegerRangeIterator(start, end);
        } else {
            return new ReverseIntegerRangeIterator(start, end);
        }
    }

    public int size() {
        return Math.abs(end - start);
    }

    private static abstract class IntegerRangeIterator
            implements Iterator<Integer> {
        protected int current;
        protected int end;

        protected IntegerRangeIterator(int current, int end) {
            this.current = current;
            this.end = end;
        }

        public void remove() {
            throw new UnsupportedOperationException
                    ("IntegerRange doesn't support removing values");
        }
    }

    public static final class ForwardIntegerRangeIterator
            extends IntegerRangeIterator {
        public ForwardIntegerRangeIterator(int current, int end) {
            super(current, end);
        }

        public boolean hasNext() {
            return current < end;
        }

        public Integer next() {
            return current++;
        }
    }

    public static final class ReverseIntegerRangeIterator
            extends IntegerRangeIterator {
        public ReverseIntegerRangeIterator(int current, int end) {
            super(current, end);
        }

        public boolean hasNext() {
            return current > end;
        }

        public Integer next() {
            return current--;
        }
    }
}